New To Detecting, Question About 1 And 2 On Vdi

[Guest]

3 hours ago, Chase Goldman said:

not just an audio suppression feature as D2 has a separate setting for that called notch.  Anyway, just wanted to clarify, however that the effect you are seeing yes not a reduction in sensitivity so much as a reduction in unmasking/recovery for those fringe targets.  In a practical sense it manifests the same as a perceived loss of sensitivity, but it’s more like cranking reactivity/recovery way up (which clips the target audio response) than turning sensitivity down. FWIW.

So in this case it might be better to discriminate with a notch to avoid clipping the signal with excessive reactivity? The recovery speed seems to me to cause greater loss at depth than for surface targets and the use of faster recovery for surface targets seems more desirable to me when there is a lot of deeper junk around. Is this correct thinking or is there a way to make shallow targets pop better when there is deeper and adjacent junk?

[Knomad]

Just remember, the magnetic field coming from the coil tapers the farther from the coil, so any deeper targets near the tip of that tapered end of the field is going to react during MUCH less of the coil travel than a surface target that will react the full width of the swing over the target. Therefore the detector has less time to react before the coil is no longer over the small end of that field, so any extra processing time like from notching out target numbers can Potentially cut into that time. It is just very demanding of the detector to try and ignore the ground, detect shallow targets, and also detect deep targets while also trying to ignore specific targets.

This is one of the big reasons I prefer no discrimination if I can avoid it, that said if there are small hot rocks everywhere close together it may be completely impractical to do that. But normally I do not use discrimination. or limit it to one or two notches, BUT I discriminate with my eyes on the display, and my ears.

[GB_Amateur]

On 2/5/2023 at 7:05 AM, Chase Goldman said:

On 2/5/2023 at 12:08 AM, Knomad said:

This is not a Theory, I have repeatedly tested the sensitivity and dept in Gold 2 Mode in the bad ground of gold baring areas. Maximum Sensitivity and depth is with No Discrimination and running as hot as you can, at these settings it acts almost like an analog detector but with target I.D readout.  The more numbers notched out the more time the detector is processing that signal instead of just reporting the signal, and so if that is a small target in ground it is fighting to find it in that extra processing can take away from it reacting to that target.  I find that if most hot ground and hot rocks read -7, -8 or-9, -8 and -9 most common, if needed I can notch out one or both of them with little loss, the more numbers notched out the more it effects both depth and sensitivity.

NOTE -- If you are hunting big targets like coins in good or modest ground you may not notice it, But try a small target at near max detection depth in other modes, then try the gold modes, in most cases you will gain depth.

 

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I agree it’s real.  Similar issues arise with Manticore while adjusting its ferrous limits (different than discrimination) and on Deus 2 - Discrimination can affect signal processing and is not just an audio suppression feature as D2 has a separate setting for that called notch.  Anyway, just wanted to clarify, however that the effect you are seeing is not a reduction in sensitivity so much as a reduction in unmasking/recovery for those fringe targets.  In a practical sense it manifests the same as a perceived loss of sensitivity, but it’s more like cranking reactivity/recovery way up (which clips the target audio response) than turning sensitivity down. FWIW.

OK, you got my interest.  For one thing, the Deus 2 works differently than the Equinox 800, I think.  (I don't know about the Manticore, yet...)  I think on the Eqx 800 there is no difference between discrimination and notching -- it's all done by notching (on the software side??).

I've been fortunate to be mentored on the Equinox 800 by some of the best gold detectorist in the USA -- Gerry McMullen and his crew of experts, Steve Herschbach, and Andrew Benson.  I don't remember any of them ever saying anything about this.  I do remember Steve recommending only to notch out the lowest bins (start with -9, and then if forced to, go higher) when the background chatter is driving you crazy.  Andrew told me to not ignore -9 signals off the bat, but rather clear/dig a bit and see if it persists before making a final decision on continuing or moving on.

I hope they will speak to this; maybe I should '@' them.

[Chase Goldman]

I'm not Gerry, Steve, or Andy, but based on my limited experience with the Nox over the past 5 years, I agree that with the Nox disc and notch settings are generally indistinguishable but in my "there are no absolutes in metal detecting" mindset, I cannot say with certainty that discing the ferrous zone will have no adverse effect on a fringe signal that is IDing near that disc setting based on my personal experience.  I know that Iron Bias definitely has an impact.  My point was really in response to a poster who said disc in modern detectors is basically like a notch...and I just wanted to point out that generalization does not hold true across the board.  On Deus and Deus 2 Disc definitely does not equal Notch.  Not sure about Legend.  On Manticore, I believe the Disc/Notch behaves similar to the Nox.  I also wanted to point out that I have seen videos that demonstrate how increasing upper ferrous limits on a Manticore can make a non-ferrous target become masked in the presence of adjacent ferrous targets, so there is definitely an effect there can cause target masking if you overdo it on the ferrous falsing cancellation filter (AKA ferrous limits) - which is really just relearning the lesson from "Filters 101 for Metal Detecting" - bottom line cliche' alert>too much of a good thing can be bad, all settings can have unanticipated adverse consequences, and there are no free lunches.  FWIW.

[GB_Amateur]

1 hour ago, Chase Goldman said:

I'm not Gerry, Steve, or Andy, but based on my limited experience with the Nox over the past 5 years, I agree that with the Nox disc and notch settings are generally indistinguishable but in my "there are no absolutes in metal detecting" mindset, I cannot say with certainty that discing the ferrous zone will have no adverse effect on a fringe signal that is IDing near that disc setting based on my personal experience.

I generally try not to discourage anyone from answering my questions by listing people I'd like to see do it, but obviously I've made exceptions on that tendency.  Rereading this thread I also realized that I've mixed up some things I've read previously about how discrimination improves or degrades certain desirable *non-discriminated* targets.  If discrimination actually is detrimental to those kinds of targets then I'm less concerned since the only time I've ever used notching discrimination with the Equinox is the situation Steve H. described -- -9 (and even -8 and -7) driving me nuts in certain spots when searching for native gold.  Discrimination through notching and/or threshold methods seems to be one of those things people either really like (and apply) or don't like (and never use).  With modern iron tone and volume, etc. capabilities I think the value of the discrimination methods of the old days has diminished, but then again I'm in the 'always want to hear all targets' camp.

I vaguely recall Tom D. on his site talking about fine tuning the ferrous masking on the Manticore to effectively enhance the ability to find certain targets, but I'm (hopefully) being vague enough here as to not mislead.  It's certainly one of the features I'm looking forward to and will be playing with early on, although not likely right away as there are some pre-requisites to learn first.

[Knomad]

To be Clear, what I said applies to the Nox 800, and in either of it's Gold Modes, and in typical gold areas, and semi to very hot ground, with smaller targets. It sounds like Steve and I do use Notching, BUT only if needed because of extreme ground causing near undetectable conditions giving typically -7, -8, and -9 readings so often without notching them out that ground is just impractical to hunt. BUT, any notching will cause clipping of multiple signals in such ground and that also can reduce sensitivity, especially to small targets.

Notching can be similar to old fashioned discrimination, But, usually is more specific than old analog Iron / Non Iron discrimination, and can be used to discriminate either ferrous or non ferrous targets, due to Processing of the signal by modern electronics. Example, For instance if you come across mass pull tabs typically #13, that number ONLY can be eliminated.  (FYI, nickels often are also a 13).

ALL of the potential loss of sensitivity and depth applies less to bigger targets in good ground, simply because the signal is cleaner, Stronger, and Easier for the processor to positively I.D at all depths.